A pathogenic role for excess NO is apparent in several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Although hypotheses have been proposed to explain motor neuron death in ALS, fundamental questions remain unanswered. One model for pathogenesis has excess NO, or its metabolites, reacting with cell-derived reactive oxygen species, resulting in protein nitration, which is often associated with tissue damage in this condition. However, little is known regarding the molecular consequences of excess NO and protein nitration. We hypothesize that excess NO and associated protein nitration cause important changes that alter the expression and function of key proteins in cells. We propose a proteomic and gene array study to globally evaluate changes in gene or protein expression, and protein nitration, in two different mouse models for ALS and in human spinal cord tissue. We will: 1) Identify proteins whose expression and/or nitration changes with disease progression; 2) Identify the nitrated residue(s) in the identified proteins; and 3) Identify genes whose expression levels change during disease progression. Candidate proteins and genes revealed by these methods will create immediate interest, and we envision growth in at least three areas: New gene and protein targets for ALS research. Preliminary results suggest a wide range of proteins may be affected, including those involved in cell-cycling, metabolism, cell-motility, cell-structure, and wound repair. There will be an immediate need to examine how changes in their expression or nitration affect function within the context of ALS. This work should lead to new targets for therapeutic intervention. Underlying mechanisms of neurodegeneration - gene and protein changes that are both unique and common to each disease model - will be identified. Common changes may reveal fundamental mechanisms for neurodegeneration, and thus impact basic research into Huntington's, Parkinson's, Alzheimer's, and SMA disease. Diagnosis and therapy-candidate genes, and proteins, should provide useful new diagnostic markers. These include markers for disease progression, treatment efficacy, and high-throughput drug discovery. Our work with non-neuronal tissue may identify markers that provide far more-convenient monitoring.